From: Andrew Cooper <andrew.cooper3@citrix.com>
To: Xen-devel <xen-devel@lists.xenproject.org>
Cc: "Edwin Török" <edvin.torok@citrix.com>,
"Andrew Cooper" <andrew.cooper3@citrix.com>,
"Christian Lindig" <christian.lindig@citrix.com>,
"David Scott" <dave@recoil.org>, "Rob Hoes" <Rob.Hoes@citrix.com>
Subject: [PATCH 5/8] tools/oxenstored: Keep /dev/xen/evtchn open across live update
Date: Tue, 22 Nov 2022 15:20:40 +0000 [thread overview]
Message-ID: <20221122152043.8518-6-andrew.cooper3@citrix.com> (raw)
In-Reply-To: <20221122152043.8518-1-andrew.cooper3@citrix.com>
From: Edwin Török <edvin.torok@citrix.com>
Closing the evtchn handle will unbind and free all local ports. The new
xenstored would need to rebind all evtchns, which is work that we don't want
or need to be doing during the critical handover period.
However, it turns out that the Windows PV drivers also rebind their local port
too across suspend/resume, leaving (o)xenstored with a stale idea of the
remote port to use. In this case, reusing the established connection is the
only robust option.
Therefore:
* Have oxenstored open /dev/xen/evtchn without CLOEXEC at start of day
* Extend the handover information with the evtchn fd, and the local port
number for each domain connection.
* Have (the new) oxenstored recover the open handle using Xeneventchn.fdopen,
and use the provided local ports rather than trying to rebind them.
When this new information isn't present (i.e. live updating from an oxenstored
prior to this change), the best-effort status quo will have to do.
Signed-off-by: Edwin Török <edvin.torok@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Christian Lindig <christian.lindig@citrix.com>
CC: David Scott <dave@recoil.org>
CC: Edwin Torok <edvin.torok@citrix.com>
CC: Rob Hoes <Rob.Hoes@citrix.com>
Merge two patches to retain bisectability. Drop changes to the evtchn bindings.
---
tools/ocaml/xenstored/domain.ml | 6 ++-
tools/ocaml/xenstored/domains.ml | 14 +++++--
tools/ocaml/xenstored/event.ml | 8 +++-
tools/ocaml/xenstored/xenstored.ml | 82 ++++++++++++++++++++++++++------------
4 files changed, 78 insertions(+), 32 deletions(-)
diff --git a/tools/ocaml/xenstored/domain.ml b/tools/ocaml/xenstored/domain.ml
index 81cb59b8f1a2..527035ffdd32 100644
--- a/tools/ocaml/xenstored/domain.ml
+++ b/tools/ocaml/xenstored/domain.ml
@@ -61,7 +61,7 @@ let string_of_port = function
| Some x -> string_of_int (Xeneventchn.to_int x)
let dump d chan =
- fprintf chan "dom,%d,%nd,%d\n" d.id d.mfn d.remote_port
+ fprintf chan "dom,%d,%nd,%d,%s\n" d.id d.mfn d.remote_port (string_of_port d.port)
let notify dom = match dom.port with
| None ->
@@ -77,6 +77,10 @@ let bind_interdomain dom =
dom.port <- Some (Event.bind_interdomain dom.eventchn dom.id dom.remote_port);
debug "bound domain %d remote port %d to local port %s" dom.id dom.remote_port (string_of_port dom.port)
+let restore_interdomain dom localport =
+ assert (dom.port = None);
+ dom.port <- Some (Xeneventchn.of_int localport);
+ debug "restored interdomain %d remote port %d to local port %s" dom.id dom.remote_port (string_of_port dom.port)
let close dom =
debug "domain %d unbound port %s" dom.id (string_of_port dom.port);
diff --git a/tools/ocaml/xenstored/domains.ml b/tools/ocaml/xenstored/domains.ml
index 17fe2fa25772..a91d2afd2a82 100644
--- a/tools/ocaml/xenstored/domains.ml
+++ b/tools/ocaml/xenstored/domains.ml
@@ -56,6 +56,7 @@ let exist doms id = Hashtbl.mem doms.table id
let find doms id = Hashtbl.find doms.table id
let number doms = Hashtbl.length doms.table
let iter doms fct = Hashtbl.iter (fun _ b -> fct b) doms.table
+let eventchn doms = doms.eventchn
let rec is_empty_queue q =
Queue.is_empty q ||
@@ -122,17 +123,22 @@ let cleanup doms =
let resume _doms _domid =
()
-let create doms domid mfn port =
+let maybe_bind_interdomain restore_localport dom =
+ match restore_localport with
+ | None -> Domain.bind_interdomain dom
+ | Some p -> Domain.restore_interdomain dom p
+
+let create doms domid mfn ?restore_localport port =
let interface = Xenctrl.map_foreign_range xc domid (Xenmmap.getpagesize()) mfn in
let dom = Domain.make domid mfn port interface doms.eventchn in
Hashtbl.add doms.table domid dom;
- Domain.bind_interdomain dom;
+ maybe_bind_interdomain restore_localport dom;
dom
let xenstored_kva = ref ""
let xenstored_port = ref ""
-let create0 doms =
+let create0 ?restore_localport doms =
let port, interface =
(
let port = Utils.read_file_single_integer !xenstored_port
@@ -146,7 +152,7 @@ let create0 doms =
in
let dom = Domain.make 0 Nativeint.zero port interface doms.eventchn in
Hashtbl.add doms.table 0 dom;
- Domain.bind_interdomain dom;
+ maybe_bind_interdomain restore_localport dom;
Domain.notify dom;
dom
diff --git a/tools/ocaml/xenstored/event.ml b/tools/ocaml/xenstored/event.ml
index ccca90b6fc4f..0159daac91f4 100644
--- a/tools/ocaml/xenstored/event.ml
+++ b/tools/ocaml/xenstored/event.ml
@@ -20,7 +20,13 @@ type t = {
mutable virq_port: Xeneventchn.t option;
}
-let init () = { handle = Xeneventchn.init (); virq_port = None; }
+let init ?fd () =
+ let handle = match fd with
+ | None -> Xeneventchn.init ~cloexec:false ()
+ | Some fd -> Xeneventchn.fdopen fd
+ in
+ { handle; virq_port = None }
+
let fd eventchn = Xeneventchn.fd eventchn.handle
let bind_dom_exc_virq eventchn = eventchn.virq_port <- Some (Xeneventchn.bind_dom_exc_virq eventchn.handle)
let bind_interdomain eventchn domid port = Xeneventchn.bind_interdomain eventchn.handle domid port
diff --git a/tools/ocaml/xenstored/xenstored.ml b/tools/ocaml/xenstored/xenstored.ml
index c5dc7a28d082..6ceab02dee1e 100644
--- a/tools/ocaml/xenstored/xenstored.ml
+++ b/tools/ocaml/xenstored/xenstored.ml
@@ -144,7 +144,7 @@ exception Bad_format of string
let dump_format_header = "$xenstored-dump-format"
-let from_channel_f chan global_f socket_f domain_f watch_f store_f =
+let from_channel_f chan global_f event_f socket_f domain_f watch_f store_f =
let unhexify s = Utils.unhexify s in
let getpath s =
let u = Utils.unhexify s in
@@ -165,12 +165,17 @@ let from_channel_f chan global_f socket_f domain_f watch_f store_f =
(* there might be more parameters here,
e.g. a RO socket from a previous version: ignore it *)
global_f ~rw
+ | "eventfd" :: eventfd :: [] ->
+ event_f ~eventfd
| "socket" :: fd :: [] ->
socket_f ~fd:(int_of_string fd)
- | "dom" :: domid :: mfn :: port :: []->
+ | "dom" :: domid :: mfn :: port :: rest ->
domain_f (int_of_string domid)
(Nativeint.of_string mfn)
(int_of_string port)
+ (match rest with
+ | [] -> None (* backward compat: old version didn't have it *)
+ | localport :: _ -> Some (int_of_string localport))
| "watch" :: domid :: path :: token :: [] ->
watch_f (int_of_string domid)
(unhexify path) (unhexify token)
@@ -189,10 +194,27 @@ let from_channel_f chan global_f socket_f domain_f watch_f store_f =
done;
info "Completed loading xenstore dump"
-let from_channel store cons doms chan =
+let from_channel store cons createdoms chan =
(* don't let the permission get on our way, full perm ! *)
let op = Store.get_ops store Perms.Connection.full_rights in
let rwro = ref (None) in
+ let eventchnfd = ref (None) in
+ let doms = ref (None) in
+
+ let require_doms () =
+ match !doms with
+ | None ->
+ let missing_eventchnfd = !eventchnfd = None in
+ if missing_eventchnfd then
+ warn "No event channel file descriptor available in dump!";
+ let eventchn = Event.init ?fd:!eventchnfd () in
+ let domains = createdoms eventchn in
+ if missing_eventchnfd then
+ Event.bind_dom_exc_virq eventchn;
+ doms := Some domains;
+ domains
+ | Some d -> d
+ in
let global_f ~rw =
let get_listen_sock sockfd =
let fd = sockfd |> int_of_string |> Utils.FD.of_int in
@@ -201,6 +223,10 @@ let from_channel store cons doms chan =
in
rwro := get_listen_sock rw
in
+ let event_f ~eventfd =
+ let fd = eventfd |> int_of_string |> Utils.FD.of_int in
+ eventchnfd := Some fd
+ in
let socket_f ~fd =
let ufd = Utils.FD.of_int fd in
let is_valid = try (Unix.fstat ufd).Unix.st_kind = Unix.S_SOCK with _ -> false in
@@ -209,12 +235,13 @@ let from_channel store cons doms chan =
else
warn "Ignoring invalid socket FD %d" fd
in
- let domain_f domid mfn port =
+ let domain_f domid mfn port restore_localport =
+ let doms = require_doms () in
let ndom =
if domid > 0 then
- Domains.create doms domid mfn port
+ Domains.create doms domid mfn ?restore_localport port
else
- Domains.create0 doms
+ Domains.create0 ?restore_localport doms
in
Connections.add_domain cons ndom;
in
@@ -229,8 +256,8 @@ let from_channel store cons doms chan =
op.Store.write path value;
op.Store.setperms path perms
in
- from_channel_f chan global_f socket_f domain_f watch_f store_f;
- !rwro
+ from_channel_f chan global_f event_f socket_f domain_f watch_f store_f;
+ !rwro, require_doms ()
let from_file store cons doms file =
info "Loading xenstore dump from %s" file;
@@ -238,7 +265,7 @@ let from_file store cons doms file =
finally (fun () -> from_channel store doms cons channel)
(fun () -> close_in channel)
-let to_channel store cons rw chan =
+let to_channel store cons (rw, eventchn) chan =
let hexify s = Utils.hexify s in
fprintf chan "%s\n" dump_format_header;
@@ -247,6 +274,7 @@ let to_channel store cons rw chan =
Unix.clear_close_on_exec fd;
Utils.FD.to_int fd in
fprintf chan "global,%d\n" (fdopt rw);
+ fprintf chan "eventchnfd,%d\n" (Utils.FD.to_int @@ Event.fd eventchn);
(* dump connections related to domains: domid, mfn, eventchn port/ sockets, and watches *)
Connections.iter cons (fun con -> Connection.dump con chan);
@@ -367,7 +395,6 @@ let _ =
| None -> () end;
let store = Store.create () in
- let eventchn = Event.init () in
let next_frequent_ops = ref 0. in
let advance_next_frequent_ops () =
next_frequent_ops := (Unix.gettimeofday () +. !Define.conflict_max_history_seconds)
@@ -375,16 +402,8 @@ let _ =
let delay_next_frequent_ops_by duration =
next_frequent_ops := !next_frequent_ops +. duration
in
- let domains = Domains.init eventchn advance_next_frequent_ops in
+ let domains eventchn = Domains.init eventchn advance_next_frequent_ops in
- (* For things that need to be done periodically but more often
- * than the periodic_ops function *)
- let frequent_ops () =
- if Unix.gettimeofday () > !next_frequent_ops then (
- History.trim ();
- Domains.incr_conflict_credit domains;
- advance_next_frequent_ops ()
- ) in
let cons = Connections.create () in
let quit = ref false in
@@ -393,15 +412,15 @@ let _ =
List.iter (fun path ->
Store.write store Perms.Connection.full_rights path "") Store.Path.specials;
- let rw_sock =
+ let rw_sock, domains =
if cf.restart && Sys.file_exists Disk.xs_daemon_database then (
- let rwro = DB.from_file store domains cons Disk.xs_daemon_database in
+ let rw, domains = DB.from_file store domains cons Disk.xs_daemon_database in
info "Live reload: database loaded";
- Event.bind_dom_exc_virq eventchn;
Process.LiveUpdate.completed ();
- rwro
+ rw, domains
) else (
info "No live reload: regular startup";
+ let domains = domains @@ Event.init () in
if !Disk.enable then (
info "reading store from disk";
Disk.read store
@@ -411,13 +430,23 @@ let _ =
if not (Store.path_exists store localpath) then
Store.mkdir store (Perms.Connection.create 0) localpath;
+ let eventchn = Event.init () in
if cf.domain_init then (
Connections.add_domain cons (Domains.create0 domains);
Event.bind_dom_exc_virq eventchn
);
- rw_sock
+ rw_sock, domains
) in
+ (* For things that need to be done periodically but more often
+ * than the periodic_ops function *)
+ let frequent_ops () =
+ if Unix.gettimeofday () > !next_frequent_ops then (
+ History.trim ();
+ Domains.incr_conflict_credit domains;
+ advance_next_frequent_ops ()
+ ) in
+
(* required for xenstore-control to detect availability of live-update *)
let tool_path = Store.Path.of_string "/tool" in
if not (Store.path_exists store tool_path) then
@@ -433,10 +462,11 @@ let _ =
Sys.set_signal Sys.sigpipe Sys.Signal_ignore;
if cf.activate_access_log then begin
- let post_rotate () = DB.to_file store cons (None) Disk.xs_daemon_database in
+ let post_rotate () = DB.to_file store cons (None, Domains.eventchn domains) Disk.xs_daemon_database in
Logging.init_access_log post_rotate
end;
+ let eventchn = Domains.eventchn domains in
let spec_fds =
(match rw_sock with None -> [] | Some x -> [ x ]) @
(if cf.domain_init then [ Event.fd eventchn ] else [])
@@ -595,7 +625,7 @@ let _ =
live_update := Process.LiveUpdate.should_run cons;
if !live_update || !quit then begin
(* don't initiate live update if saving state fails *)
- DB.to_file store cons (rw_sock) Disk.xs_daemon_database;
+ DB.to_file store cons (rw_sock, eventchn) Disk.xs_daemon_database;
quit := true;
end
with exc ->
--
2.11.0
next prev parent reply other threads:[~2022-11-22 15:21 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-22 15:20 [PATCH 0/8] Oxenstored live update fixes Andrew Cooper
2022-11-22 15:20 ` [PATCH 1/8] tools/oxenstored: Fix incorrect scope after an if statement Andrew Cooper
2022-11-23 14:50 ` Andrew Cooper
2022-11-22 15:20 ` [PATCH 2/8] tools/ocaml/evtchn: OCaml 5 support, fix potential resource leak Andrew Cooper
2022-11-22 15:20 ` [PATCH 3/8] tools/ocaml/evtchn: Add binding for xenevtchn_fdopen() Andrew Cooper
2022-11-22 15:20 ` [PATCH 4/8] tools/ocaml/evtchn: Extend the init() binding with a cloexec flag Andrew Cooper
2022-11-22 15:20 ` Andrew Cooper [this message]
2022-11-23 10:59 ` [PATCH 5/8] tools/oxenstored: Keep /dev/xen/evtchn open across live update Christian Lindig
2022-11-22 15:20 ` [PATCH 6/8] tools/oxenstored: Log live update issues at warning level Andrew Cooper
2022-11-22 15:20 ` [PATCH 7/8] tools/oxenstored: Set uncaught exception handler Andrew Cooper
2022-11-22 15:20 ` [PATCH 8/8] tools/oxenstored/syslog: Avoid potential NULL dereference Andrew Cooper
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